A vehicle is a driving apparatus configured to move on the road by driving vehicle wheels.
The vehicle includes internal combustion engine vehicles that burn petroleum fuel, e.g., gasoline and diesel to generate a mechanical power so as to drive using the mechanical power, and environment-friendly vehicles that drive using electricity to reduce fuel consumption and hazardous gas emission.
The environment-friendly vehicles include electric vehicles provided with a battery charged by an electric power source and a motor to rotate the wheels using the electricity stored in the battery and to drive vehicle wheels by using the rotation of the motor, and hybrid vehicles and hydrogen fuel cell electric vehicles provided with an engine, a battery and a motor to drive the wheels by controlling the mechanical power of the engine and the electrical power of the motor.
The hybrid vehicle can drive in the electric vehicle (EV) mode of using the power of the motor, or in the hybrid electric vehicle (HEV) mode of using the power of the engine and the motor. In addition, the hybrid vehicle performs regenerative braking, in which the battery is charged by recovering braking energy and the inertial energy through generation operations of the motor when braking or when coasting by the inertia.
As for the battery of the hybrid vehicles, the state of charge (SOC) of the battery is variably controlled by the engine operation according to the driving state. However, the engine operation is flexible and thus it is difficult to immediately apply the driving state to the state of charge (SOC) control. Accordingly, there may be difficulties in controlling the state of charge (SOC) of the vehicle's battery.
The difficulty in the state of charge (SOC) control may be generated because the control of the battery is not flexible in urban area, where congestion and traffic signal stop sections induce low efficiency, unlike in the medium and high speed sections having high charging efficiency, and in the ultra-high speed section having the low charging efficiency.
Accordingly, as for the battery of the hybrid vehicle, due to the idle charge, the entrance of the full load, and the frequent exiting of the state of charge (SOC) normal areas may occur, and thus the fuel efficiency of the engine may be reduced.